1. Field of the Invention
The present invention relates to a spindle motor for rotatably driving a recording disk.
2. Description of the Related Art
Generally, motors such as spindle motors comprise a housing, a hub which is rotatable relative to the housing, a rotor magnet mounted on the hub, and a stator facing the rotor magnet. The stator has a stator core fixed to the housing, and an armature coil is wound as required. A recording disk, such as a magnetic disk, is mounted on the hub, and the recording disk is driven to rotate in one piece with the hub in a predetermined direction.
In this type of spindle motor, a lead from an armature coil is formed of a plurality of wires. Such a lead is electrically connected, for example, to one end section of a flexible board, which extends to outside the housing. Connection devices, such as connectors or the like, mounted on the other end section thereof are connected to external connectors. Such a construction is complex, and steps are required to electrically connect the lead section of a coil with the flexible board. The operation is troublesome to perform. Furthermore, when the flexible board is extended outside the housing, the construction is complex, and a process for insulating the housing from the flexible board must be considered.
In this type of spindle motor, recording disks are mounted as follows: a plurality of female screw holes are formed at intervals in the periphery of the end wall section of the hub. Through holes are formed in a clamp member for fastening the recording disk, the through holes of which correspond to the female screw holes. The recording disk is fixedly attached as required by screwing fixing screws to the female screw holes of the hub through the through holes of the clamp member.
However, since the female screw holes disposed on the hub are shaped in such a way that there is a dead end in the middle of the inside thereof, a surface treatment solution does not sufficiently penetrate into the tapered section (i.e., the front end section) of a screw section. Therefore, there is a possibility that an untreated part remains, which may cause contamination or rust.
To solve the above-described problems, female screw holes can also be formed in a shape (not shown) that they pass through the hub in the axial direction thereof. When it is so constructed, the above-mentioned surface treatment solution sufficiently penetrates into the tapered section of a screw hole. Thus, there is only a slight possibility that any part will remain untreated.
Yet, because the through hole in the hub connects the interior of the spindle motor to the disk chamber, there is a danger that grease of the bearing, unclean air, gas, or the like inside the spindle motor will penetrate the disk chamber.
In the above-described motor, the inner edge of the stator core is supported in the housing. The outer edge thereof floats freely from the housing. Therefore, in such a supporting structure, when vibration of a specific frequency is applied thereto, the stator core may resonate, causing an axial deflection. When such a deflection occurs, a head used for reading/writing information of a recording disk cannot track on the surface of the tracks, causing an error.